Radio-frequency identification (RFID) tags have many uses, one of which is to track the progress of goods across a supply chain. When an item is tagged, the tag is assigned a unique “tag identifier” and a corresponding entry is written into a database. Later, when the tag is observed, the tag identifier can be used as an index to the item in the database. Thus, if the tag is observed at a specific times by a specific readers located in a warehouse, for example, the time and reader information can be entered into the database in association with the tag identifier of the observed tag, so as to track location and/or motion of the item throughout the warehouse. Operations on a larger scale have also been implemented, whereby goods are tracked across cities and even continents.
Tags can be one-time programmable or read/writable. Read/writable tags have advantages over one-time programmable tags because they allow the same tag to be reprogrammed with a different tag identifier multiple times, such as at different points of the supply chain. With the ability to reprogram a tag, it is now possible to encode information directly on the tag, such as historical data about the parties in the supply chain that have handled the item, or whether the item is considered to have entered or exited a given warehouse, and so on.
Before reprogramming a given tag, however, it may be necessary to obtain more specific information about the associated item by consulting the database. In fact, the database itself may contain data that is intended to be downloaded to the tag, such as new information acquired or generated since the last time that the tag was (re)programmed. However, when the item whose tag is to be reprogrammed is physically in motion (e.g., on a truck or a train), the time required to consult the database, obtain new information for that tag and effect reprogramming may cause an unwanted delay in the item's progress along the supply chain.
Against this background, there is a need in the industry for an improved system and method for tracking items associated with read/writable tags.